Download Arctic Shorebirds in North America : a Decade of Monitoring by Jonathan Robert Bart, Victoria Helen Johnston PDF

By Jonathan Robert Bart, Victoria Helen Johnston

Each yr shorebirds from North and South the US migrate hundreds of thousands of miles to spend the summer time within the Arctic. There they feed in coastline marshes and estuaries alongside essentially the most efficient and pristine coasts at any place. With quite a bit on hand meals they can reproduce virtually explosively; and as iciness techniques, they retreat south in addition to their offspring, to come back to the Arctic the subsequent spring. This awesome development of circulation and task has been the item of in depth examine by means of a world workforce of ornithologists who've spent a decade counting, surveying, and watching those shorebirds. during this vital artificial paintings, they deal with a number of questions on those migratory poultry populations. what number birds occupy Arctic ecosystems each one summer season? How lengthy do vacationing shorebirds linger ahead of heading south? How fecund are those birds? the place precisely do they migrate and the place precisely do they go back? Are their populations transforming into or shrinking? the result of this research are an important for higher figuring out how environmental guidelines will effect Arctic habitats in addition to the far-ranging iciness habitats utilized by migratory shorebirds.

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The x−i were calculated as the simple means of the means/plot because sometimes plots at a camp were not all surveyed the same number of times by rapid surveyors. Camps were widely distributed across the study area, so they were treated as a simple random sample (rather than a stratified random sample). ^ was Under this assumption, the variance of R estimated as ͧ ^− ^ x−, y−) 2Cov( V^(y− ) _________ 2 V(x ) Ϫ V^(R^) ϭ R^ ____ ϩ _____ − xy x−2 y−2 ͨ (12) where 1 2− ^ − 1 2− 1 − − ___ ___ ^ − − V^(x− ) ϭ ___ m s (xi), V( y ) ϭ m s (yi), Cov(x , y ) ϭ m cov(xi, yi) and s2 and coˆv indicate the sample variances and covariances, respectively.

96). Least Sandpipers are considered to be uncommon breeders in the eastern Aleutians (Gibson and Byrd 2007). The species was not recorded in the YDSA or SSA. Although they are spottily distributed in the interior of the Yukon–Kuskokwim Delta, they do not breed in the coastal fringe where we sampled (B. J. McCaffery, pers. ). Pectoral Sandpiper Pectoral Sandpipers were recorded only on the YDSA, where they are a common spring migrant in late May, but only a rare breeder (McCaffery, pers. ). Ten pairs and 19 single birds were recorded, mainly in wetlands.

2). 3). A few dozen pairs and a handful of nests were recorded, but most observations were of single birds and nearly all records were from wetlands. The estimated number of pairs breeding in surveyed plots was 191. In the central part of the Yukon–Kuskokwim Delta, Semipalmated Sandpipers only occur regularly in the lower coastal meadows (R. E. , and C. R. Ely, pers. , B. J. McCaffery pers. ). A few isolated pairs were reported from the sand dunes in the vicinity of Dall Point north of Hooper Bay (Brandt 1943).

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